What is the overload principle value used in NMES strengthening when MVIC cannot be measured?

• A. 25% MVIC
• B. 50% MVIC or maximum tolerable contraction
• C. 75% MVIC
• D. 100% MVIC

Answer: (B)

The idea is to apply a training burden strong enough to elicit strength gains without causing undue fatigue or discomfort. When you can’t measure MVIC, prescribing about half of MVIC, or the greatest contraction the person can tolerate, provides a practical balance: it delivers enough motor unit recruitment to drive improvement while keeping fatigue and pain within manageable limits given NMES’s nonvoluntary and often fatiguing nature. Start at this level and progressively increase as tolerance and strength improve. For comparison, a much smaller percentage would likely be insufficient to induce gains, while higher percentages (and certainly maximal efforts) are harder to sustain safely when MVIC can’t be quantified.